<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .not-allow{
            color: red;
            font-size: 4rem;
        }
        .allow{
            color: green;
            font-size: 4rem;
        }
        .warn{
            color: yellowgreen;
            font-size: 4rem;
        }
    </style>
</head>
<body>
    {%  if age > 18 %}
        <div class="allow">OK to in</div>
    {% elif age == 18 %}
        <div class="warn">Need your parents to accompany</div>
    {% else %}
        <div class="not-allow">Not allowed</div>
    {% endif %}
    <hr>
      <ol>
    {% for book in books %}

    <li>{{ book.name }}: {{ book.author }}</li>
    {% endfor %}
       </ol>
</body>
</html>